金属离子负载对表面改性PI薄膜热分解温度的影响

Effect of Metal Ion Loading on Thermal Decomposition Temperature of Surface Modified Polyimide Films

采用KOH溶液对均苯四甲酸酐/4,4’-二氨基二苯醚(PMDA/ODA)基聚酰亚胺(PI)薄膜进行表面碱解开环改性处理,乙酸酸化后,在PI表面得到聚酰胺酸(PAA)表面改性层,随后通过离子交换反应在PAA层中分别引入了K+、Na+、Ca2+、Mg2+、Ag+、Al3+这6种金属离子。通过傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)和电感耦合等离子发射光谱(ICP)考察了不同金属离子的离子交换过程。同时,通过氮气氛围下的热重(TG)分析考察了不同金属离子的载入对PI薄膜热分解温度的影响。结果表明:金属离子的负载量与其化合价呈反比关系,该离子交换反应严格按照离子电荷1∶1进行;同时,强碱金属离子K+、Na+对PI薄膜有明显降解作用,导致PI薄膜热分解温度明显下降,而碱性较弱金属离子Ca2+、Mg2+、Ag+、Al3+则对PI薄膜的热分解温度影响非常微弱。金属离子对薄膜热分解温度的影响与其对应氢氧化物的碱性(pKb)呈正相关,即K+>Na+>>Ca2+≈Mg2+>Ag+≈Al3+。

The surface of the pyromellitic anhydride/4,4'-diaminodiphenyl ether(PMDA/ODA)-based polyimide(PI)film was subjected to alkali-cleaving and ring-opening treatment with potassium hydroxide(KOH)solution.After acidification with acetic acid,a surface-modificated layer of polyamic acid(PAA)was obtained on the surface of PI.Six different metal ions(K+,Na+,Ca2+,Mg2+,Ag+and Al3+)were introduced into the PAA layer via ion exchange reaction.The ion exchange processes of different metal ions were investigated by Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM)and inductively coupled plasma emission spectroscopy(ICP).As a result,the load amount of metal ion showed a completely inverse relationship with its valence,indicating that the ion exchange reaction was carried out exactly according to the ionic charge ratio of 1∶1.Meanwhile,the thermal gravimetric(TG)analyzer under a nitrogen atmosphere was performed to investigate the effect of different metal ions on the thermal decomposition temperature of PI film.It was found that the strong alkali metal ions,K+and Na+,provided obvious degradation effects on the PI film,which caused a significant decrease in the thermal decomposition temperature of the PI film.However,the weaker alkali metal ions such as Ca2+,Mg2+,Ag+and Al3+exhibited a rather weak influence on the thermal decomposition temperature of the PI film.The effect of metal ions on the thermal decomposition temperature of the film was positively correlated with the alkalinity(pKb)of its corresponding hydioxide,ie K+>Na+>>Ca2+≈Mg2+>Ag+≈Al3+.